An enteric preparation is widely known as one of DDS technologies concerning pharmaceuticals for oral dosing.
An enteric preparation is designed to achieve medical effect by enteric absorption without releasing the drug ingredient in the stomach. By suppressing release of the drug ingredient in the stomach, decomposition of the drug ingredient by gastric acid is prevented and incidence of adverse drug reactions in the stomach is decreased. As a result, it is become possible to increase availability of the drug ingredient.
In general, pH in the stomach is from 1.2 to 3.5, while pH in the intestine is from 5 to 8. Therefore, it is known that an enteric preparation which does not dissolve under the pH in the stomach but dissolves under the pH in the intestine can be produced utilizing the difference in the pH values.
As such an enteric preparation, tablets and capsules have widely been developed heretofore. In these preparations, a coating layer is formed using an enteric base ingredient on a nucleus containing a drug ingredient, or a matrix is formed using the enteric base ingredient and a drug ingredient.
However, water is required for taking a tablet or capsule. Even in case that these preparations are taken together with water, these are difficult to be swallowed when their size is large. In addition, swallowing a capsule is sometimes difficult, since it easily adheres to mucous membrane. Particularly, it is difficult for infants and elderly people to take a table and capsule, because their swallowing function is inferior.
On the other hand, a gel and jelly can be taken with favorable feelings. Accordingly, a technology using polysaccharide having gelation function and thickening effect has been developed.
For example, Japanese Unexamined Patent Publication No. 2004-173675 discloses a technology that bacteria are enclosed in a solid which is hardened with a coagulating agent, and the bacteria are taken alive into the intestine. As the coagulating agent, pectin and alginic acid are described, however, these are just merely exemplified. Further, this technology is not a one for releasing a drug ingredient in the intestine.
Japanese Unexamined Patent Publication No. 4-258260 discloses a polysaccharide gel and a polysaccharide gel composition, which are prepared by forcible hydration of polysaccharide such as pectin and alginate under a high pressure treatment. In the publication, a calcium-rich alginic acid gel is exemplified as an enteric gel. The gel is a dietary food, which separates into calcium and alginic acid in the stomach and allows calcium to be absorbed in the intestine. Namely, the gel is not for releasing a drug ingredient in the intestine.
Japanese Unexamined Patent Publication No. 4-27352, Japanese Unexamined Patent Publication No. 61-207328 and Japanese Unexamined Patent Publication No. 58-172313 disclose enteric soft capsules using pectin or alginate. These are technologies for making a film of the soft capsule or for coating a surface of the soft capsule using polysaccharide such as pectin and alginate. In addition, pectin and alginate are just merely exemplified as an enteric polysaccharide.
Japanese Unexamined Patent Publication No. 2004-507581 discloses a film composition in which pectin is used as an enteric material. The composition is used as a base material of a hard capsule.
Further, WO2002/015878 discloses an aqueous suspension containing a hardly-soluble drug, polyvinyl pyrolidone and a water-soluble anionic polymer. The technology is simply for stably dispersing the drug in an aqueous solution, and there is no description of enteric property at all in the document.